Read up on basic statistics (find a free online Stats 101 type class). Your tests are "independent events", but the more often you perform the test the more likely the average will be close to the expected value.
Odds of flipping a coin the same side 23 times in a row: 1 in 4,194,304
Odds of getting a yellow ball 2:1 favorite 17 times in a row: 1 in 985
Odds of getting a yellow ball 4:1 favorite 30 times in a row: 1 in 807
You might also want to quickly read this: Gambler's fallacy - Wikipedia, the free encyclopedia