logarithm regression equation

The table shows Taiwan's nuclear power generation data in billions of killowatt hours. Let x=5 represent 1980, x=10 rep. 1985 and so on.

**Year** **Energy produced**

1980 7.8

1985 27.8

1990 31.6

1995 33.9

1) find natural logarithm regression equation for the data.

y=-20.52 + 19.05 ln(x)

I got this in my calculator..is it correct? Thanks!

2) Predict when the nuclear power generation will reach 40 billion kilowatt hours.

I have a question -- do you plug 40 billion into the x or the y? I think y, because it is total power, but just checking my work.

When I plug 40 billion in for y, I come up with 21.47, which would be year 1996.

Am I correct?