other income increased in 2011 versus 2010 due to higher gains from real estate sales , lower environmental costs associated with non-operating properties and the comparative impact of premiums paid for early redemption of long-term debt in the first quarter of 2010 .
interest expense 2013 interest expense decreased in 2012 versus 2011 reflecting a lower effective interest rate in 2012 of 6.0% ( 6.0 % ) versus 6.2% ( 6.2 % ) in 2011 as the debt level did not materially change in 2012 .
interest expense decreased in 2011 versus 2010 due to a lower weighted-average debt level of $ 9.2 billion versus $ 9.7 billion .
the effective interest rate was 6.2% ( 6.2 % ) in both 2011 and 2010 .
income taxes 2013 higher pre-tax income increased income taxes in 2012 compared to 2011 .
our effective tax rate for 2012 was relatively flat at 37.6% ( 37.6 % ) compared to 37.5% ( 37.5 % ) in 2011 .
income taxes were higher in 2011 compared to 2010 , primarily driven by higher pre-tax income .
our effective tax rate remained relatively flat at 37.5% ( 37.5 % ) in 2011 compared to 37.3% ( 37.3 % ) in 2010 .
other operating/performance and financial statistics we report key performance measures weekly to the association of american railroads ( aar ) , including carloads , average daily inventory of freight cars on our system , average train speed , and average terminal dwell time .
we provide this data on our website at www.up.com/investors/reports/index.shtml .
operating/performance statistics railroad performance measures reported to the aar , as well as other performance measures , are included in the table below : 2012 2011 2010 % (  % ) change 2012 v 2011 % (  % ) change 2011 v 2010 .

<i>2012</i>
<i>2011</i>
<i>2010</i>
<i>% Change 2012 v 2011</i>
<i>% Change 2011 v 2010</i>
Average train speed (miles per hour)
26.5
25.6
26.2
4 %
(2)%
Average terminal dwell time (hours)
26.2
26.2
25.4
- %
3 %
Average rail car inventory (thousands)
269.1
272.9
274.4
(1)%
(1)%
Gross ton-miles (billions)
959.3
978.2
931.4
(2)%
5 %
Revenue ton-miles (billions)
521.1
544.4
520.4
(4)%
5 %
Operating ratio
67.8
70.7
70.6
(2.9)pts
0.1 pts
Employees (average)
45,928
44,861
42,884
2 %
5 %
Customer satisfaction index
93
92
89
1 pt
3 pts

average train speed 2013 average train speed is calculated by dividing train miles by hours operated on our main lines between terminals .
average train speed , as reported to the association of american railroads ( aar ) , increased 4% ( 4 % ) in 2012 versus 2011 .
efficient operations and relatively mild weather conditions during the year compared favorably to 2011 , during which severe winter weather , flooding , and extreme heat and drought affected various parts of our network .
we continued operating a fluid and efficient network while handling essentially the same volume and adjusting operations to accommodate increased capital project work on our network compared to 2011 .
the extreme weather challenges in addition to increased carloadings and traffic mix changes , led to a 2% ( 2 % ) decrease in average train speed in 2011 compared to 2010 .
average terminal dwell time 2013 average terminal dwell time is the average time that a rail car spends at our terminals .
lower average terminal dwell time improves asset utilization and service .
average terminal dwell time remained flat in 2012 compared to 2011 , despite a shift in traffic mix to more manifest shipments , which require more switching at terminals .
average terminal dwell time increased 3% ( 3 % ) in 2011 compared to 2010 .
additional volume , weather challenges , track replacement programs , and a shift of traffic mix to more manifest shipments , which require additional terminal processing , all contributed to the increase .
average rail car inventory 2013 average rail car inventory is the daily average number of rail cars on our lines , including rail cars in storage .
lower average rail car inventory reduces congestion in our yards and sidings , which increases train speed , reduces average terminal dwell time , and improves rail car utilization .
despite a shift in traffic mix from coal to shale-related and automotive shipments with longer .

Question: Analyse this data from a financial earnings document. what is the 2011 total interest expense in billions based on the weighted-average debt level and effective interest rate?
Choices:
0.5704
0.3844
0.0006
0.552
148.3871
Correct choice index: 0