pre_text: Deferred revenue primarily consists of amounts that have been invoiced but not yet been recognized as revenue and consists of performance obligations pertaining to support and subscription services. During the years ended December 31, 2019 and 2018, we recognized revenue of $63.2 million and $60.2 million, related to deferred revenue at the beginning of the period. Deferred revenue consisted of the following (in thousands):
table: December 31, 2019 December 31, 2018
table: Deferred revenue:
table: Products $6,593 $5,216
table: Services 94,571 92,750
table: Total deferred revenue 101,164 97,966
table: Less: current portion (62,233) (63,874)
table: Non-current portion $38,931 $34,092
question: Analyse this data from a financial earnings document. What is the total non-current portion of the deferred revenue between 2018 and 2019?