82 | 2017 form 10-k a reconciliation of the beginning and ending amount of gross unrecognized tax benefits for uncertain tax positions , including positions impacting only the timing of tax benefits , follows . reconciliation of unrecognized tax benefits:1 years a0ended a0december a031 .

Table:
( millions of dollars ) | years ended december 31 , 2017 | years ended december 31 , 2016
balance at january 1, | $ 1032 | $ 968
additions for tax positions related to current year | 270 | 73
additions for tax positions related to prior years | 20 | 55
reductions for tax positions related to prior years | -27 ( 27 ) | -36 ( 36 )
reductions for settlements2 | -9 ( 9 ) | -24 ( 24 )
reductions for expiration of statute of limitations | 2014 | -4 ( 4 )
balance at december 31, | $ 1286 | $ 1032
amount that if recognized would impact the effective tax rate | $ 1209 | $ 963
1 foreign currency impacts are included within each line as applicable .
2 includes cash payment or other reduction of assets to settle liability .
we classify interest and penalties on income taxes as a component of the provision for income taxes .
we recognized a net provision for interest and penalties of $ 38 million , $ 34 million and $ 20 million during the years ended december 31 , 2017 , 2016 and 2015 , respectively .
the total amount of interest and penalties accrued was $ 157 million and $ 120 million as of december a031 , 2017 and 2016 , respectively .
on january 31 , 2018 , we received a revenue agent 2019s report from the irs indicating the end of the field examination of our u.s .
income tax returns for 2010 to 2012 .
in the audits of 2007 to 2012 including the impact of a loss carryback to 2005 , the irs has proposed to tax in the united states profits earned from certain parts transactions by csarl , based on the irs examination team 2019s application of the 201csubstance-over-form 201d or 201cassignment-of-income 201d judicial doctrines .
we are vigorously contesting the proposed increases to tax and penalties for these years of approximately $ 2.3 billion .
we believe that the relevant transactions complied with applicable tax laws and did not violate judicial doctrines .
we have filed u.s .
income tax returns on this same basis for years after 2012 .
based on the information currently available , we do not anticipate a significant increase or decrease to our unrecognized tax benefits for this matter within the next 12 months .
we currently believe the ultimate disposition of this matter will not have a material adverse effect on our consolidated financial position , liquidity or results of operations .
with the exception of a loss carryback to 2005 , tax years prior to 2007 are generally no longer subject to u.s .
tax assessment .
in our major non-u.s .
jurisdictions including australia , brazil , china , germany , japan , mexico , switzerland , singapore and the u.k. , tax years are typically subject to examination for three to ten years .
due to the uncertainty related to the timing and potential outcome of audits , we cannot estimate the range of reasonably possible change in unrecognized tax benefits in the next 12 months. .

Question: what was the average provision for interest and penalties for the period december 31 , 2015 to 2017 , in millions?
Answer: 30.7
Calculation: add(38, 34), add(20, #0), divide(#1, const_3)