Curve fit Exponential Rise data in Excel 2007

[GlennBurks]

I am trying to curve fit data that represents an exponential rise (the data increases sharply before leveling out and looks like an "n"). Example data is shown below. It appears to me that excel only curve fits exponential growth data (the data increases slowly before increasing sharply (data looks like a "u"). Is it possible to obtain a best curve fit for the data below and obtain the R-squared value with equation within Excel 2007?

4/13/2006 1
7/13/2006 11
10/13/2006 21
1/13/2007 31
4/13/2007 38
7/13/2007 45
10/13/2007 52
1/13/2008 58
4/13/2008 64
7/13/2008 70
10/13/2008 75
1/13/2009 80
4/13/2009 82
7/13/2009 84
10/13/2009 85
1/13/2010 86
4/13/2010 87
7/13/2010 88
10/13/2010 89
1/13/2011 89

[GlennBurks]

I just posted on how to curve fit exponential rise data in Excell 2007 but now I have the form of the equation. Example data is as follows:

4/13/2006 1
7/13/2006 11
10/13/2006 21
1/13/2007 31
4/13/2007 38
7/13/2007 45
10/13/2007 52
1/13/2008 58
4/13/2008 64
7/13/2008 70
10/13/2008 75
1/13/2009 80
4/13/2009 82
7/13/2009 84
10/13/2009 85
1/13/2010 86
4/13/2010 87
7/13/2010 88
10/13/2010 89
1/13/2011 89

The form of the equation to best fit this data is:

Y = C + A(1-e^-bx)

where Y is the date and x is the numerical value. C (the offset) is zero in my case.

My question is that I am wondering if it is possible to do this automatically in Excel 2007 because from what I could determine, only the exponential growth or decay forms are available (equation in the form y = Ae^bx or y=Ae^-bx).

Any help would be most appreciated and thank you kindly in advance!