management 2019s discussion and analysis net interest income 2013 versus 2012 . net interest income on the consolidated statements of earnings was $ 3.39 billion for 2013 , 13% ( 13 % ) lower than 2012 . the decrease compared with 2012 was primarily due to lower average yields on financial instruments owned , at fair value , partially offset by lower interest expense on financial instruments sold , but not yet purchased , at fair value and collateralized financings . 2012 versus 2011 . net interest income on the consolidated statements of earnings was $ 3.88 billion for 2012 , 25% ( 25 % ) lower than 2011 . the decrease compared with 2011 was primarily due to lower average yields on financial instruments owned , at fair value and collateralized agreements . see 201cstatistical disclosures 2014 distribution of assets , liabilities and shareholders 2019 equity 201d for further information about our sources of net interest income . operating expenses our operating expenses are primarily influenced by compensation , headcount and levels of business activity . compensation and benefits includes salaries , discretionary compensation , amortization of equity awards and other items such as benefits . discretionary compensation is significantly impacted by , among other factors , the level of net revenues , overall financial performance , prevailing labor markets , business mix , the structure of our share-based compensation programs and the external environment . the table below presents our operating expenses and total staff ( which includes employees , consultants and temporary staff ) . .

year ended december 2013: compensation and benefits: 12613
brokerage clearing exchange anddistribution fees: 2341
market development: 541
communications and technology: 776
depreciation and amortization: 1322
occupancy: 839
professional fees: 930
insurance reserves1: 176
other expenses: 2931
total non-compensation expenses: 9856
total operating expenses: 22469
total staff at period-end: 32900
year ended december 2012: compensation and benefits: 12944
brokerage clearing exchange anddistribution fees: 2208
market development: 509
communications and technology: 782
depreciation and amortization: 1738
occupancy: 875
professional fees: 867
insurance reserves1: 598
other expenses: 2435
total non-compensation expenses: 10012
total operating expenses: 22956
total staff at period-end: 32400
year ended december 2011: compensation and benefits: 12223
brokerage clearing exchange anddistribution fees: 2463
market development: 640
communications and technology: 828
depreciation and amortization: 1865
occupancy: 1030
professional fees: 992
insurance reserves1: 529
other expenses: 2072
total non-compensation expenses: 10419
total operating expenses: 22642
total staff at period-end: 33300

1 . related revenues are included in 201cmarket making 201d in the consolidated statements of earnings . goldman sachs 2013 annual report 45 .

Questions:
what percentage did the net interest income in 2012 represent in relation to the 2011 one?
and what was that 2012 net interest income?
considering this net interest income and the percentage of the 2011 one it represented, what was the 2011 net interest income?
and from 2012 to 2013, what was the change in the staff number?
what was that staff number in 2012?
what is, then, that change as a percentage of this 2012 number?

Answers:
75%
3.88
5.17
500
32400
1.5%