GLD ETF vs. Gold Bullion Earnings

Hi Forum!

I'm a new investor in PM's and notice that the return on investment since 2007 for the ETF (GLD) is much greater than that for a 100 oz. of gold bullion. From Jan 2007 thru Sept 2011, the ROI on GLD has been 175% vs. 118% for 100 oz. gold bullion if calculated from the NAV and spot prices. Why don't these %'s match up more closely? If my numbers are correct, then investing in PM ETFs is the way to go vs. holding PM bullion.

GLD ETF, NAVs: 1/2007 is 63.58; 9/2011 is 175.80

100 oz. Gold spot prices: 1/7 at $830 oz.; 9/11 at $1,872 oz.

Thanks,

Peter