Sochi 2014
Total number of tests: 2,453
Pre-games tests: 1,269
Post Competition tests: 1,184
Analysis: 1,944 urine samples will be collected (full menu of prohibited substances), 572 analyzed for EPO. 509 blood samples will be collected (hGH, EPO, blood transfusions)
Anti-Doping Rule Violations (ADRVs):

(In WADC valid from 2015 it says in Article 17 that "No anti-doping rule violation proceeding may be commenced against an Athlete or other Person unless he or she has been notified of the anti-doping rule violation as provided in Article 7, or notification has been reasonably attempted, within ten years from the date the violation is asserted to have occurred." This article is retroactive according to Article 25.2 in the World Anti-Doping Code version 4.)
Sources:
USA Today: http://www.usatoday.com/story/sports/olympics/sochi/2014/02/05/world-anti-doping-agency-david-howman-sochi-olympics/5229239/
BBC: http://www.usatoday.com/story/sports/olympics/sochi/2014/02/05/world-anti-doping-agency-david-howman-sochi-olympics/5229239/
WADA: http://www.wada-ama.org/Documents/World_Anti-Doping_Program/WADP-The-Code/Code_Review/Code%20Review%202015/Code%20Final%20Draft/WADC-2015-final-draft-EN.pdf

Vancouver 2010
Total number of athletes: 2,566 (1044 women, 1522 men)
Total number of tests: 2,149
Pre-games tests: 892
Post Competition: 1,257
Analysis: 1,742 urine samples, 507 analyzed for EPO. 407 blood samples will be collected.
ADRVs: 1 (We have registered 3) Ice Hockey (2) (Public Warnings), Cross Country Skiing (1) (2 year suspension)
Samples are held for eight years for possible follow-up.

Torino 2006
Total number of athletes: 2,508 (960 women, 1,548 men)
Total number of tests: 1,219
Pre-games: 428
(Urine: 261, EPO: 253, hGH: 154, hbocs: 13, B/T: 12)
Post Competition: 791
(Urine: 658, EPO: 187, hGH: 0, hbocs, 133, B/T: 133)
ADRVs: 7 (We have registered 6)

Salt Lake City 2002
Total number of athletes: 2,399 (886 women, 1,513 men)
Total number of tests: Approx 800 (IOC reports 700)
ADRVs: 7 (We have registered 11)

Earlier games:
1968 Grenoble: 86 tests, 0 number of cases
1972 Sapporo: 211 tests, 1 (Ice hockey, ephedrine)
1976 Innsbruck: 390 tests, 2 (cross country skiing, ephedrine, codeine)
1980 Lake Placid: 440 tests, 0 number of cases
1984 Sarajevo: 424 tests, 1 (cross country skiing, methandienone)
1988 Calgary: 492 tests, 1 (ice hockey, testosterone)
1992 Albertville: 522, 0 number of cases
1994 Lillehammer: 529, 0 number of cases
1998 Nagano: 621, 0 number of cases (The game had one snowboarder testing positive for cannabis, only received a public warning/reprimand)

Sport statistics:
Cross-country skiing 13
Ice Hockey 7
Biathlon 2
Alpine Skiing 1
Bobsleigh 1
Speed skating 1

Countries:
Austria 8
Russian Federation 5
Belarus 3
Poland 2
Slovakia 1
Latvia 1
Spain 1
United Kingdom 1
Mongolia 1
Czech Republic 1

(Sources: IOC, Canada National Olympic Committee, International Ice Hockey Federation, World Anti-Doping Agency, The Anti-Doping Database)