$**$Question $4\mathrm{.}5.**$ Finally, let's revisit the $`$population$\_$by$\_$year$`$ DataFrame from earlier in the lab. Compute the year when the world population first went above $7$ billion.

year$\_$population$\_$crossed$\_7\_$billion $=$ population$\_$by$\_$year$[$population$\_$by$\_$year.get$(\text{'}$Year$\text{'})>7000000000].$shape$[0]$

year$\_$population$\_$crossed$\_7\_$billion