interest expense 2013 interest expense increased in 2014 versus 2013 due to an increased weighted- average debt level of $ 10.8 billion in 2014 from $ 9.6 billion in 2013 , which more than offset the impact of the lower effective interest rate of 5.3% ( 5.3 % ) in 2014 versus 5.7% ( 5.7 % ) in 2013 .
interest expense decreased in 2013 versus 2012 due to a lower effective interest rate of 5.7% ( 5.7 % ) in 2013 versus 6.0% ( 6.0 % ) in 2012 .
the increase in the weighted-average debt level to $ 9.6 billion in 2013 from $ 9.1 billion in 2012 partially offset the impact of the lower effective interest rate .
income taxes 2013 higher pre-tax income increased income taxes in 2014 compared to 2013 .
our effective tax rate for 2014 was 37.9% ( 37.9 % ) compared to 37.7% ( 37.7 % ) in 2013 .
higher pre-tax income increased income taxes in 2013 compared to 2012 .
our effective tax rate for 2013 was 37.7% ( 37.7 % ) compared to 37.6% ( 37.6 % ) in 2012 .
other operating/performance and financial statistics we report a number of key performance measures weekly to the association of american railroads ( aar ) .
we provide this data on our website at www.up.com/investor/aar-stb_reports/index.htm .
operating/performance statistics railroad performance measures are included in the table below : 2014 2013 2012 % (  % ) change 2014 v 2013 % (  % ) change 2013 v 2012 .

<i>2014</i>
<i>2013</i>
<i>2012</i>
<i>% Change</i> <i>2014 v 2013</i>
<i>% Change</i><i>2013 v 2012</i>
Average train speed (miles per hour)
24.0
26.0
26.5
(8)%
(2)%
Average terminal dwell time (hours)
30.3
27.1
26.2
12 %
3 %
Gross ton-miles (billions)
1,014.9
949.1
959.3
7 %
(1)%
Revenue ton-miles (billions)
549.6
514.3
521.1
7 %
(1)%
Operating ratio
63.5
66.1
67.8
(2.6)pts
(1.7)pts
Employees (average)
47,201
46,445
45,928
2 %
1 %

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 , decreased 8% ( 8 % ) in 2014 versus 2013 .
the decline was driven by a 7% ( 7 % ) volume increase , a major infrastructure project in fort worth , texas and inclement weather , including flooding in the midwest in the second quarter and severe weather conditions in the first quarter that impacted all major u.s .
and canadian railroads .
average train speed decreased 2% ( 2 % ) in 2013 versus 2012 .
the decline was driven by severe weather conditions and shifts of traffic to sections of our network with higher utilization .
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 increased 12% ( 12 % ) in 2014 compared to 2013 , caused by higher volumes and inclement weather .
average terminal dwell time increased 3% ( 3 % ) in 2013 compared to 2012 , primarily due to growth of manifest traffic which requires more time in terminals for switching cars and building trains .
gross and revenue ton-miles 2013 gross ton-miles are calculated by multiplying the weight of loaded and empty freight cars by the number of miles hauled .
revenue ton-miles are calculated by multiplying the weight of freight by the number of tariff miles .
gross ton-miles , revenue ton-miles and carloadings all increased 7% ( 7 % ) in 2014 compared to 2013 .
gross ton-miles and revenue ton-miles declined 1% ( 1 % ) in 2013 compared to 2012 and carloads remained relatively flat driven by declines in coal and agricultural products offset by growth in chemical , autos and industrial products .
changes in commodity mix drove the year-over-year variances between gross ton- miles , revenue ton-miles and carloads. .

Question: Analyse this data from a financial earnings document. holding weighted- average debt level as the same as 2013what would the interest expense be in 2014 in billions?
Choices:
445872
0.0051
23368.1664
181.1321
0.5088
Correct choice index: 4