Until we get the official statistics, we can only provide an educated guess.
The following is a sampling.
(a) RIT Alumni in Myanmar
The largest alumni are in Myanmar.
Until a few years ago, there was no formal RIT Alumni Association.
Many sayas and alums served as President and Executive Committee members in Myanmar Engineering Society (MES). MES is not an NGO. It is an NPO.
SPZP-2004 was held in December, 2004 in Yangon about the same time as the ASEAN Engineering Conference. The mild earth quake did not deter the attendees of the [then] largest SPZP.
Thanks in part to H.E. U Aye Myint (EP72), a true Home Coming was hosted at SPZP-2012.
Around SPZP-2012, Sayagyi U Aung Khin and Sayagyi U Ba Than served as Patrons of the newly formed Mechanical Engineers Association.
Swel Daw Yeik Foundation was established in 2013.
Shwe YaDu celebrations were held in 2014. It includes the planting of fifty Swel Daw Bins. Several Shwe YaDu benches were donated by alumni in Myanmar and overseas.
RITAA hosted SPZP-2016. There was free food and entertainment.
(b) RIT Alumni in Singapore
Singapore has the largest alums outside of Myanmar. The Singapore RIT Alumni Association has helped organize three SPZPs in December 2002, April 2007, and December 2010.
Saya U Moe Aung (Tekkatho Moe War, EE63) chaired SPZP-2002 and SPZP-2010. U Nyan Win Shwe (William, M72) chaired SPZP-2007.
The organizers for the SPZPs include Saya Dr. Tin Hlaing (M63), Saya U Tin Hlaing (ChE65), U Tint Lwin (Daniel, M69), Sayama Daw Tin Tin Myint (ChE70), Saya U Aung (C70), Saya U Tin Lin (ChE72) , Saya Dr. Soe Thein (C75), U Moe Myint (M76), and Ko Maung Aunt (M).
Saya U Moe Aung and his team published the commemorative issues of “Swel Daw Yeik Sar Saung” for SPZP-2002, SPZP-2007, and SPZP-2010.
The association also lent helping hand for the SPZP in Yangon in December 2004. Ko Zaw Tun Naing (Aero 95) was designated as the point of contact in Singapore for SPZP-2012.
There used to be Civil and Electrical Engineering web sites for the Singapore RIT Alumni.
(c) RIT Alumni in Thailand
Several sayas including Sayagyi U Ba Toke and Sayagyi U Khin Aung Kyi taught in Thailand. Saya Dr. Win Tin served as Associate Dean at Assumption University (formerly ABAC).
Saya U Sein Maung (EE63), Saya U Tin Shwe (EP66) and many other sayas taught at ABAC and other Thai universities.
Some alums such as U Win Hlaing (C68) also taught in Thailand.
Saya U Aung Myaing (ChE72) and Daw Gyn Yu (ChE72) hosted micro-gatherings for the alumni visiting Bangkok.
(d) RIT Alumni in Australia and New Zealand
There is no formal RIT Alumni Association in Australia and New Zealand. But, the alums participate in the Myanmar Engineering Associations. U “Henry” Thet Tun (M75), U Sein Win *C80), U “Abel” Aye Win Hlaing (La La, EE7x), Daw “Christine” Phyu Phyu Latt (A70), … can write about the RIT Alumni Activities in Oz (Down Under).
Saya Dr. Koung Nyunt (A67, GBNF), U Stanley Saw (M71), U Dennis Kyaw Thu (C73 now in Canada) , … wrote about the RIT Alumni Activities in New Zealand.
(e) RIT Alumni in Japan
U Thein Ngwe (ChE75) co-founded RITAJ (RIT Alumni in Japan). He was helped by Ko Win Myint (EDC83) for some time. But, I have not heard from them for a long time. U Thein Ngwe, Saya Dr. Myo Khin, … can write about the RIT Alumni Activities in Japan.
(f) RIT Alumni in Canada
U Tha Aung and Daw Kinsa Maw Naing organized several alum gatherings in Canada. They are currently working on projects in Myanmar,
Sayagyi U Aung Khin, Sayagyi Dr. Aung Gyi, Saya Des Rodgers, Saya U Kyaw Myint, U Htein Win (Chauk Pay, RIT swimming, water polo, and rowing), U “Jasper” Aung Lwin (RIT rowing), U Zaw Oo … reside in Canada.
(g) RIT Alumni in UK
There have been mini-gatherings in UK. Ko Nyunt Aung, Ma “Betsy” Sandar Bo, Ma “Yvonne” Tin Tin Win, Ma “Pauk Pauk” Aye Aye Than, Ma Khin May Than, Ko “Norman” Myint Khine, Dr. Aung Shein, … reside in UK.
Ma “Alice” Saw Yu Tint often visits UK to see her daughter and grandchild.
(h) RIT Alumni in US
Alums in the US formed “RIT Alumni International” before SPZP-2000. The founder/members include Saya Allen Htay (GBNF), Saya U San Tun, Saya K C Chiu, Saya U Nyo Win, Saya “George” Maung Maung, Saya U Myat Htoo, Saya “James” Thein Aung, U “Henry” Myint Lwin, U Benny Tan, U Maurice Chee, U Khin Maung Zaw, and me.
But, it was dormant for some time.
NorCal RIT Alumni Association was formed with Saya U George Maung Maung (ChE66) as President and U Stanislaus Lious (M67) as Chair of the Board of Directors (BOD).
U Kaung Kaung Oo (Gordon, M83) is the Past President. U Aung Myint Oo (EC84) is the current President.
Saya U Myat Htoo (C68) is the current Chair of BOD.
Alums participate in BAPS (for Northern California) and BASES (for Southern California).
Los Angeles hosted the 2015 Alumni Gathering. U Thaung Sein (Steeve Kay, EC70) was the matching sponsor for US $30,000.
Two mini-gatherings (one in DC area, and another near Niagara Falls) were held for the RIT Alums in East Coast.
Ko Ivan Lee (Khin Maung Oo, M69) has hosted RIT-UCC gatherings for several years. This year’s gathering will be on June 30, 2018.
(i) RIT Alumni in other countries
Some sayas and alums are known to have resided or worked in Germany, Malaysia, Taiwan, Brunei, Cambodia, Botswana, Jamaica, …