So, unless I mis-counted that's it for successful missions to the surface of Mars. Others include landers from:
Mars 2 in 1971 (USSR) - never made it to Mars to deploy its lander;
Mars 3 in 1971 (USSR) - 20 seconds of lander operation after touchdown;
Mars 6 in 1973 (USSR) - failed just before touchdown;
Mars 7 in 1973 (USSR) - lander separated early and missed the planet ....;
Phobos 2 in 1989 (Russia) - lost contact before deploying lander toward the moon Phobos;
Mars 96 in 1996 (Russia) - orbiter, lander, and two surface penetrators never made it out of Earth orbit;
Mars Polar Lander in 1999 (USA) - premature engine shutdown before landing, crashed;
Mars Express/Beagle 2 in 2003 (ESA) - orbiter still on station but lander failed (used some design/instruments from Mars 96);
Phobos-Grunt in 2011 (Russia) - upper stage failure, never made it out of Earth orbit.
So, from the Planetary Society (
www.planetary.org) the score, including all Mars missions, stands at:
Humans - 13
Mars - 20
and 6 ties (partial successes)
Yogi