## Is your feature request related to a problem?

Compare year to date
![image](https://user-images.githubusercontent.com/1727427/101010122-8044ed00-3562-11eb-8be1-8462250ef97a.png)

With last 90 days [(link)](https://app.posthog.net/insights?display=ActionsBar&events=%5B%7B%22id%22%3A%22%24pageview%22%2C%22name%22%3A%22%24pageview%22%2C%22type%22%3A%22events%22%2C%22order%22%3A0%2C%22math%22%3A%22total%22%7D%5D&shown_as=Lifecycle&actions=%5B%5D&properties=%5B%7B%22key%22%3A%22%24current_url%22%2C%22value%22%3A%22https%3A%2F%2Fposthog.com%22%2C%22operator%22%3A%22not_icontains%22%2C%22type%22%3A%22event%22%7D%2C%7B%22key%22%3A%22id%22%2C%22value%22%3A71%2C%22type%22%3A%22cohort%22%7D%5D&interval=week&date_from=-90d)
![image](https://user-images.githubusercontent.com/1727427/101010537-9f437f00-3562-11eb-8e9f-a7e75f0018f5.png)


## Describe the solution you'd like



## Describe alternatives you've considered



## Additional context



#### *Thank you* for your feature request – we love each and every one!

posthog/queries/lifecycle.py
DATE_TRUNC(%(interval)s,
                                        min("posthog_event"."timestamp") AT TIME ZONE 'UTC') earliest
            FROM ({earliest_events}) posthog_event
            JOIN
            (SELECT person_id,
                    distinct_id
                FROM posthog_persondistinctid
                WHERE team_id = %(team_id)s) pdi on posthog_event.distinct_id = pdi.distinct_id
            {action_join}
            WHERE team_id = %(team_id)s
                AND {event_condition}
            GROUP BY person_id
        ) earliest ON e.person_id = earliest.person_id
    ) e
    WHERE status = %(status)s
    AND DATE_TRUNC(%(interval)s, %(target_date)s) = subsequent_day
    LIMIT %(limit)s OFFSET %(offset)s
"""
def get_interval(period: str) -> Union[timedelta, relativedelta]:
    if period == "hour":
        return timedelta(hours=1)
    elif period == "day":
        return timedelta(days=1)
    elif period == "week":
        return timedelta(weeks=1)
    elif period == "month":
        return relativedelta(months=1)
    else:
        raise ValueError("{} not supported".format(period))
def get_time_diff(