Correlation Coefficient with data that has missing info

Hi there,

I have 2 sets of data, im trying to find the correlation coefficient of both sets of data. However, in the set of data there are some missing blanks like below

Dates 1 Price 1 Dates 2 Price 2
3/18/1996 10 3/18/1996 13.5
3/19/1996 10.125 3/19/1996 14
3/20/1996 10.125 #N/A #N/A
3/22/1996 10.25 3/22/1996 14
3/25/1996 10.25 3/25/1996 14.0625
#N/A #N/A 3/26/1996 13.25
3/27/1996 10.25 3/27/1996 13.1875
3/28/1996 10.25 3/28/1996 13.125
3/29/1996 10.25 3/29/1996 13.5


How do i find the correlation coefficient without having to add the missing data inside?

Thanks alot guys!