pre_text: The long-term portion of the Company’s unrecognized tax benefits at March 31, 2019 and 2018 was $622,000 and $619,000, respectively, of which the timing of the resolution is uncertain. As of March 31, 2019 and 2018, $2.5 million and $2.1 million, respectively, of unrecognized tax benefits had been recorded as a reduction to net deferred tax assets. As of March 31, 2019, the Company’s net deferred tax assets of $6.7 million are subject to a valuation allowance of $6.7 million. It is possible, however, that some months or years may elapse before an uncertain position for which the Company has established a reserve is resolved. A reconciliation of unrecognized tax benefits is as follows: The unrecognized tax benefit balance as of March 31, 2019 of $599,000 would affect the Company’s effective tax rate if recognized.
table: Year Ended March 31, 
table: 2019 2018 2017
table: (In thousands)
table: Unrecognized tax benefits, beginning of period $2,735 $2,714 $2,055
table: Additions based on tax positions related to current year 371 520 730
table: Additions based on tax positions related to prior years 13 — —
table: 2017 Tax Act and tax rate re-measurement   — (499) —
table: Reductions based on tax positions related to prior years   (17) — —
table: Lapses during the current year applicable to statutes of limitations   — — (71)
table: Unrecognized tax benefits, end of period $3,102 $2,735 $2,714
question: Analyse this data from a financial earnings document. What is the average Additions based on tax positions related to prior years between 2017-2019?