Firstly, it depends on the 'cable car' meaning - I take it you mean the ones hanging above the ground, instead of the San Francisco-style ones which were named one of the most dangerous forms of transportation around.
So on to the type you're talking about. Safety regulations will surely differ in every country. However, since many are made in Switzerland and exported elsewhere (including the 50 and 100-person gondola at Grouse Mountain in Vancouver), I've found some statistics out of Switzerland:
For every 1000 passengers in 2008, there were 0.000005 deaths. If I'm doing my maths correctly, that is one in every 200,000,000 passengers, or a 99.9999995% non-death carry rate :)
In 2009, same chart - there were no deaths.
The same page looks at the deaths in rail, trolleybus and other forms of transportation, all of which have a higher accident and death rate. So basically, if you're willing to get into a method of transportation on the ground, statistically, you're safer off travelling by gondola/cable-car :)