Cristiano Ronaldo's 2019 can be looked at in two ways.

On the one hand, it's been a solid year for the 34-year-old as he became the first player in history to win the Premier League, La Liga and Serie A crowns in his career.

And he even added further fuel to the GOAT (greatest of all-time) debate by winning his second trophy for Portugal with some heroic displays in the UEFA Nations League this summer.

However, the year wasn't without its disappointment and Ronaldo failed to deliver the Champions League title for Juventus that he so desired after moving to Italy.

That, and the fact his goal-scoring has actually suffered a decline, finding the net fewer times in Serie A than Krzysztof Piatek, Duvan Zapata and Fabio Quagliarella last season.

Ronaldo's 2019 in review

And sadly for the proud Portuguese, that trend has continued into the 2019/20 campaign as he finds himself seven strikes behind Ciro Immobile in the race for the Golden Boot.

So, is it time we realised that Ronaldo is finally on the way down? Well, now is the perfect chance to answer that question with the Juventus man having played his last game of 2019.

For both club and country, Ronaldo has found the net on 39 occasions during the calendar year.

Worrying goal-scoring trend

While most strikers would be incredibly proud of that tally, it pales in comparison to the 50 that his eternal rival Lionel Messi has managed - and when contrasted with his own record, too.

In fact, Marca highlighted a worrying fact on Christmas Day, showing that Ronaldo has actually been on a goal-scoring slump for six years on the bounce. Check out the statistics below:

2013: 69 goals

2014: 61 goals

2015: 57 goals

2016: 55 goals

2017: 53 goals

2018: 49 goals

2019: 39 goals

Ouch. Perhaps the most worrying fact is that, while Ronaldo has been steadily plateauing in general, his 2019 tally of 39 strikes marks the biggest drop from the entire era.

It goes without saying that his numbers are still superhuman and we're not seriously calling years where he bagged over 50 goals some sort of disaster, but the trend is there for everyone to see.

And it's especially damning when you consider Messi has only 'declined' by a single goal in 2019 and has done something that Ronaldo hasn't since 2013: improved on a previous year.

GIVEMESPORT's Kobe Tong

Even one of the greatest footballers - and athletes, for that matter - in history can't escape father time.

We're talking about a man who has done everything in his power to make age appear nothing more than a number, but such a focus on physicality breeds reliance as much as success.

Although Ronaldo is more than just a world-class athlete, stripping away that extra 1% of physical ability is enough to chip off a few goals with each year. 

Sure, there are still flashes of athletic brilliance such as his header at Sampdoria, but he doesn't have it within him to buzz around the pitch at 100mph like he did at Real Madrid anymore.

However, if we take anything from this downhill trend of Ronaldo's, let it be that we should treasure this incredible footballer and remember that he won't be around forever.