koajs add a public template value for every route

I write a website using koajs and ejs template engine, I found I need to render a same year when access different route, like this:

router.get('/', async (ctx, next) => {
    await ctx.render('index', {
        currentYear: templates.currentYear, // <--this line will repeat many times
        sub_title: 'Index',
    }));
}).get('/notfound', async (ctx, next) => {
    await ctx.render('404', {
        sub_title: 'Not Found',
        currentYear: templates.currentYear, // <--this line will repeat many times
    });
})

can I get rid of it? I tried this way:

const templatesObject = {
    currentYear: new Date().getFullYear(),
}

// use a addTemplate function to merge the template object
const addTemplate = (obj) => {return {...templatesObject, ...obj}}

// index
router.get('/', async (ctx, next) => {
    await ctx.render('index', addTemplate({
        sub_title: 'Index', // <-- now I need not to write currentYear many times
    }));
})

but I wonder if I can have better way to solve it? PS: the current year may be an example, it can be a website name, a user information, etc.