英Independent紙のコラムの一節・because we happen to know～
手元に質問が溜まっていますので、決着のついていない質問が前にありますが、同時並行して質問させていただきます。
英 Independent紙のユーモアコラムからです。筆者は Rebecca Tyrrel氏。12月22日の「Everybody hates us. And if we met ourselves at a party, we'd hate us, too」
と題するもの。
質問箇所は第3段落ですが、念のため第4段落まで引用します。
In March, Matthew instigates the "Why haven't you done anything about the garden?" row. In the middle of July, he asks, "How do you know I'm not anaphylactic if I've never actually been stung by a wasp?"; and in December we embark on the "We have no friends" debate. I knew this particularly festive discussion was imminent from the look on Matthew's face as he sat on the sofa, the twinkling tree lights reflected so prettily in his whisky tumbler. He was staring forlornly at the mantelpiece.
"Six cards," he muttered. "Just the six. Six, six, six. No more, no less. Just six."
"But that is a 50 per cent improvement on last year," I console. "No, it's not!" he snaps back. "It's bloody not. Last year we had four. And this year we only hung on to those two," he inclines his head towards a brace of cards on a side table, "because we happen to know that it's 12 years since the people they were actually meant for lived at this address."
He then points out that the card in the middle of the mantelpiece is from a local Indian restaurant, and we were lucky to get that since the last time he had any dealings with them, it was to complain about a "cataclysmically oversalted king-prawn dhansak", which he suggested they might like to force-feed to the chef with the aid of a plunger. I say nothing about any of this, I am biding my time until I am obliged to offer the ritual denial of the proposal about to be made: that we have no friends.
上記第3段落の文章 And this year we only hung on to those two,（省略）because we happen to know that it's 12 years since the people they were actually meant for lived at this address で、筆者の意味するところはどういうことなのかをご教示ください。
なお、質問箇所の前までの文章の意味はざっと次の通りと思います。
夫のマシューは「なんで庭をほったらかしにしてるの」論争を3月に開始する。6月の半ばには、「蜂に刺されたことがなくてどうして自分が急性アレルギー反応を起こさないとわかるんだ」と聞く。12月は「自分達には友人がいない」論を繰り広げる。私には楽しさ格別のこの議論がいよいよ持ち出されることは、ソファに陣取った夫の顔つきから明らかだった。ウイスキーを注いだタンブラーにはクリスマスツリーの光の点滅が鮮やかに映っている。夫はマントルピースを寂しげに眺めている。
「クリスマスカードは6枚だ」と夫はつぶやく。「たったの6枚。6枚、6枚、6枚。それ以上でもなければそれ以下でもない。6枚だ」。
「でも去年よりは50パーセントの改善だわ」と私はなだめる。「いや、とんでもない」と即座に夫はかみつく。サイドテーブルにある2枚のカードに顔を向けて「全然違う。去年は4枚だった。And this year we only hung on to those two, because we happen to know that it's 12 years since the people they were actually meant for lived at this address.」
