<PRE><B>Question 327556</B>
1970 / 10.0
1980 / 18.3
1985 / 20.6
1990 / 23.0
1995 / 24.7
2000 / 26.7
Square the data above to get,
1970/	100
1980/	334.89
1985/	424.36
1990/	529
1995/	610.09
2000/	712.89
Fit that to a straight line using EXCEL Chart Wizard,
{{{y=20.136x-39552}}}
Take the square root of that equation,
{{{y=sqrt(20.136x-39552)}}}
Check the data using the equation comparing to the original data,
1970/	10.0/10.8
1980/	18.3/17.8
1985/	20.6/20.4
1990/	23.0/22.8
1995/	24.7/24.9
2000/	26.7/26.8
</PRE>