Mahjong Ratios and Percentages

One thing I hate most about losing a computer game like Solitaire or Mahjong is that I know my stats will take a hit. My computer keeps track of how many games I have played and won, and then it figures out the percentage of games I have won.

The more games I lose, the lower that percentage gets. If I win again later, the percentage will creep up, but after one loss, it will never again be 100%. It could get close though if I play 101 games and lose only one.

Let's say I lost another game of Mahjong...

1. What would be ratio of games won to games played be then?
2. What would be my percentage of wins?
3. When could I possibly have seen that same percentage before?
4. When may I see it again in the future?
5. How many games would I have to win to raise my stats above 50%?