It struck me that while there is some dramatic visual evidence of PIRA's attacks on customs during the Troubles (e.g. Newry Customs Office in 1972), and there's even some mention in Wikipedia of such attacks being performed even in the earlier Border Campaign (which wasn't all about attacks on the border proper, but the Saor Uladh and some IRA "splinter group" burned or bombed at least six customs posts in 1956), I could not find any quantitative estimates how often the IRA attacked border posts (of various kinds), including customs.
During the Troubles, the IRA seems to have often attacked the British army cratering operations (of minor roads) while they were ongoing. But that's a somewhat different issue.
So, are there any statistics on kind of attacks/operations that the IRA conducted on the border installations proper? Were customs buildings and officials often the target, or maybe more of a "collateral damage", e.g. due to an attack on the army personnel guarding it?
FWIW, the 1972 Newry bomb attack doesn't seem to have been the first on that installation, there was another the year before:
Saturday 27 November 1971: Two Customs officials, Ian Hankin (27) a Protestant and James O'Neill (39) a Catholic, were shot by an Irish Republican Army (IRA) sniper who fired upon a British Army (BA) patrol investigating a bomb attack on a Customs Post near Newry, County Armagh.