Complex sentence: Since 2000, when two female drivers (St. James and Sarah Fisher) started the race, female participation has been growing, and since that year, at least one woman has started every race, and at least two have started every race since 2007.
Split into simpler sentences: Since 2000, when two female drivers (St. James and Sarah Fisher) started the race, female participation has been growing. Since that year, at least one woman has started every race, and at least two have started every race since 2007.