Thanks everybody.
Just for reference, I've decided to download the whole medline and parse the file locally, as I wanted to avoid making hundreds of thousands query updated.
First, I've downloaded the files from ftp://ftp.ncbi.nlm.nih.gov/pubmed/baseline
Since these are xml files, I've extracted the publication date using this XSLT template:
<xsl:stylesheet version="1.0" xmlns:xsl="<a href=" http:="" www.w3.org="" 1999="" XSL="" Transform"="" rel="nofollow">http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" encoding="UTF-8"/>
<xsl:template match="PubmedArticle">
<xsl:value-of select="MedlineCitation/PMID"/>,<xsl:value-of select="MedlineCitation/Article/Journal/JournalIssue/PubDate/Year"/>,<xsl:value-of select="MedlineCitation/DateCompleted/Year"/>
</xsl:template>
</xsl:stylesheet>
Then, transformed all the xml files using GNU/parallel and xsltproc. This provided a number of txt files containing three columns (pmid, date of record creation, and date of publication completed), which was merged and formatted with an R script, to get a final 2-columns file with pmid and year.
Interesting fact: I can now officially demonstrate that the PMID does not directly correlate with the publication date, e.g. two papers with consecutive PMID may have been published in completely different years.
that's not always the case...
I see! That's too bad, it means I really need to get a table then.