what's the meaning of these numbers?

18,100,000,000
3,520,000,000
5,040,000,000
5,990,000,000
7,210,000,000
3,060,000,000
2,370,000,000
2,190,000,000
9,010,000,000
2,060,000,000
2,500,000,000
4,400,000,000
5,460,000,000
4,110,000,000
4,800,000,000
4,350,000,000
1,890,000,000
2,740,000,000
8,050,000,000
6,970,000,000
2,610,000,000
3,400,000,000
3,390,000,000
3,770,000,000
3,190,000,000
2,340,000,000